Tinidazole degradation assisted by solar radiation and iron-doped silica xerogels

A. Acosta-Rangel, M. Sánchez-Polo, A.M.S. Polo, J. Rivera-Utrilla, M.S. Berber-Mendoza
Chemical Engineering Journal, 344, 21-33., 2020.


The main objective of this study was to assess the photoactive properties of iron-doped silica xerogels under solar radiation. For this purpose, silica xerogels (XGS) were doped with different doses of Fe(III) by the sol-gel method. Tinidazole (TNZ) was considered as model compound for the degradation study. XGS samples were texturally and chemically characterized by N2 (77 K), standard test sieves, XRD, FTIR, SEM, HRTEM, PL, XPS, and DRS. The results showed that in aqueous solution of 0.4M Fe(III), XGS was doped with 3.64% iron and contained 33.01% silicon and 63.36% oxygen (XGS-Fe(III)-0.4 M). The addition of Fe(III) modified the textural properties of the xerogels. Thus, XGS-Fe(III)-0.4M had a smaller specific area (587m2 g?1) than non-doped XGS-BCO (645.92m2 g?1), with a decrease in pore volume and average pore diameter of 50% and 63.6%, respectively. The band-gap energy (Eg) value was reduced from 3.55 eV (XGS-BCO) to 2.32 eV (XGS-Fe(III)-0.4 M) due to the inclusion of iron zoned in the form of iron oxy-hydroxide. Therefore, this is a photoactive material under solar radiation, with an Eg value<4 eV. The percentage TNZ degradation was 41% for XGS-BCO and 68% for XGS-Fe (III)-0.4M after 1 h of treatment. Previous irradiation of XGS-Fe(III)-0.4M increased the percentage TNZ degradation to 98%. The radicals generated in the process were quantified. The degradation rate was increased at higher XGS-Fe(III) doses and neutral pH.